Methods, devices and systems for activated carbon supercapacitors with macroporous electrodes

ABSTRACT

Energy storage devices comprising carbon-based electrodes and/or redox electrolytes are disclosed herein. In some embodiments, the carbon-based electrodes comprise laser-scribed activated carbon comprising one or more micro-channels. In some embodiments, the redox electrolytes comprise a ferricyanide/ferrocyanide redox couple. Also described are processes, methods, protocols and the like for manufacturing carbon-based electrodes comprising micro-channels for use in high energy storage devices such as supercapacitors, and for manufacturing high energy storage devices comprising redox electrolytes.

CROSS REFERENCE

This application is a divisional of U.S. patent application Ser. No.15/848,522, filed Dec. 20, 2017, which claims the benefit of U.S.Provisional Application No. 62/438,377, filed Dec. 22, 2016, whichapplications are incorporated herein by reference in their entireties.

BACKGROUND

Electrochemical supercapacitors (ESCs) have garnered attention due totheir high power density, excellent low temperature performance, andessentially unlimited number of charge/discharge cycles. While ESCsdemonstrate excellent electrochemical performance, the high cost per kWhlimits the wide-spread adoption of ESCs. Compared with lithium ionbatteries, some current supercapacitors exhibit a 10 times higher costper kWh. The high cost per kWh is a major concern for capacitive energystorage and currently prevents the adoption of supercapacitors toreplace batteries in many applications.

SUMMARY

The instant inventors have recognized a need for higher energy densitystorage devices to power numerous electronic devices including portableelectronic devices. Provided herein, in certain embodiments, arecarbon-based materials, fabrication and manufacturing methods andprocesses, and systems for high energy density storage with improvedperformance. The devices, methods, and systems described herein havenumerous potential commercial applications.

In one aspect, the present disclosure provides for an electrodecomprising a current collector and an activated carbon substrate. Insome embodiments, the current collector comprises a carbon substrate. Insome embodiments, the carbon substrate comprises amorphous carbon.

In some embodiments, the activated carbon substrate is chemicallyactivated, physically activated, or any combination thereof. In someembodiments, the activated carbon substrate comprises activated carbon,activated charcoal, activated carbon cloth, activated carbon fiber,activated glassy carbon, activated carbon nanofoam, activated carbonaerogel, or any combination thereof. In some embodiments, the activatedcarbon substrate is activated carbon cloth. In some embodiments, theactivated carbon substrate comprises carbon derived from one or morecoconut shells.

In some embodiments, the current collector is metallic. In someembodiments, the current collector is non-metallic. In some embodiments,the current collector comprises aluminum, nickel, copper, platinum,iron, steel, graphite, carbon cloth, or any combination thereof. In someembodiments, the current collector comprises aluminum.

In some embodiments, the electrode comprises one or more channels.

In some embodiments, the one or more channels have a pore size of about0.05 micrometers to about 500 micrometers. In some embodiments, the oneor more channels have a pore size at least about 0.05 micrometers. Insome embodiments, the one or more channels have a pore size at mostabout 500 micrometers. In some embodiments, the one or more channelshave a pore size of about 0.05 micrometers to about 0.1 micrometers,about 0.05 micrometers to about 0.5 micrometers, about 0.05 micrometersto about 1 micrometer, about 0.05 micrometers to about 5 micrometers,about 0.05 micrometers to about 10 micrometers, about 0.05 micrometersto about 50 micrometers, about 0.05 micrometers to about 100micrometers, about 0.05 micrometers to about 200 micrometers, about 0.05micrometers to about 300 micrometers, about 0.05 micrometers to about400 micrometers, about 0.05 micrometers to about 500 micrometers, about0.1 micrometers to about 0.5 micrometers, about 0.1 micrometers to about1 micrometer, about 0.1 micrometers to about 5 micrometers, about 0.1micrometers to about 10 micrometers, about 0.1 micrometers to about 50micrometers, about 0.1 micrometers to about 100 micrometers, about 0.1micrometers to about 200 micrometers, about 0.1 micrometers to about 300micrometers, about 0.1 micrometers to about 400 micrometers, about 0.1micrometers to about 500 micrometers, about 0.5 micrometers to about 1micrometer, about 0.5 micrometers to about 5 micrometers, about 0.5micrometers to about 10 micrometers, about 0.5 micrometers to about 50micrometers, about 0.5 micrometers to about 100 micrometers, about 0.5micrometers to about 200 micrometers, about 0.5 micrometers to about 300micrometers, about 0.5 micrometers to about 400 micrometers, about 0.5micrometers to about 500 micrometers, about 1 micrometer to about 5micrometers, about 1 micrometer to about 10 micrometers, about 1micrometer to about 50 micrometers, about 1 micrometer to about 100micrometers, about 1 micrometer to about 200 micrometers, about 1micrometer to about 300 micrometers, about 1 micrometer to about 400micrometers, about 1 micrometer to about 500 micrometers, about 5micrometers to about 10 micrometers, about 5 micrometers to about 50micrometers, about 5 micrometers to about 100 micrometers, about 5micrometers to about 200 micrometers, about 5 micrometers to about 300micrometers, about 5 micrometers to about 400 micrometers, about 5micrometers to about 500 micrometers, about 10 micrometers to about 50micrometers, about 10 micrometers to about 100 micrometers, about 10micrometers to about 200 micrometers, about 10 micrometers to about 300micrometers, about 10 micrometers to about 400 micrometers, about 10micrometers to about 500 micrometers, about 50 micrometers to about 100micrometers, about 50 micrometers to about 200 micrometers, about 50micrometers to about 300 micrometers, about 50 micrometers to about 400micrometers, about 50 micrometers to about 500 micrometers, about 100micrometers to about 200 micrometers, about 100 micrometers to about 300micrometers, about 100 micrometers to about 400 micrometers, about 100micrometers to about 500 micrometers, about 200 micrometers to about 300micrometers, about 200 micrometers to about 400 micrometers, about 200micrometers to about 500 micrometers, about 300 micrometers to about 400micrometers, about 300 micrometers to about 500 micrometers, or about400 micrometers to about 500 micrometers. In some embodiments, the oneor more channels have a pore size about 0.05 micrometers, about 0.1micrometers, about 0.5 micrometers, about 1 micrometer, about 5micrometers, about 10 micrometers, about 50 micrometers, about 100micrometers, about 200 micrometers, about 300 micrometers, about 400micrometers, or about 500 micrometers.

In some embodiments, the electrode has an areal capacitance of about 50mF/cm² to about 800 mF/cm². In some embodiments, the electrode has anareal capacitance of at least about 50 mF/cm². In some embodiments, theelectrode has an areal capacitance of at most about 800 mF/cm². In someembodiments, the electrode has an areal capacitance of about 50 mF/cm²to about 75 mF/cm², about 50 mF/cm² to about 100 mF/cm², about 50 mF/cm²to about 150 mF/cm², about 50 mF/cm² to about 200 mF/cm², about 50mF/cm² to about 250 mF/cm², about 50 mF/cm² to about 300 mF/cm², about50 mF/cm² to about 400 mF/cm², about 50 mF/cm² to about 500 mF/cm²,about 50 mF/cm² to about 600 mF/cm², about 50 mF/cm² to about 700mF/cm², about 50 mF/cm² to about 800 mF/cm², about 75 mF/cm² to about100 mF/cm², about 75 mF/cm² to about 150 mF/cm², about 75 mF/cm² toabout 200 mF/cm², about 75 mF/cm² to about 250 mF/cm², about 75 mF/cm²to about 300 mF/cm², about 75 mF/cm² to about 400 mF/cm², about 75mF/cm² to about 500 mF/cm², about 75 mF/cm² to about 600 mF/cm², about75 mF/cm² to about 700 mF/cm², about 75 mF/cm² to about 800 mF/cm²,about 100 mF/cm² to about 150 mF/cm², about 100 mF/cm² to about 200mF/cm², about 100 mF/cm² to about 250 mF/cm², about 100 mF/cm² to about300 mF/cm², about 100 mF/cm² to about 400 mF/cm², about 100 mF/cm² toabout 500 mF/cm², about 100 mF/cm² to about 600 mF/cm², about 100 mF/cm²to about 700 mF/cm², about 100 mF/cm² to about 800 mF/cm², about 150mF/cm² to about 200 mF/cm², about 150 mF/cm² to about 250 mF/cm², about150 mF/cm² to about 300 mF/cm², about 150 mF/cm² to about 400 mF/cm²,about 150 mF/cm² to about 500 mF/cm², about 150 mF/cm² to about 600mF/cm², about 150 mF/cm² to about 700 mF/cm², about 150 mF/cm² to about800 mF/cm², about 200 mF/cm² to about 250 mF/cm², about 200 mF/cm² toabout 300 mF/cm², about 200 mF/cm² to about 400 mF/cm², about 200 mF/cm²to about 500 mF/cm², about 200 mF/cm² to about 600 mF/cm², about 200mF/cm² to about 700 mF/cm², about 200 mF/cm² to about 800 mF/cm², about250 mF/cm² to about 300 mF/cm², about 250 mF/cm² to about 400 mF/cm²,about 250 mF/cm² to about 500 mF/cm², about 250 mF/cm² to about 600mF/cm², about 250 mF/cm² to about 700 mF/cm², about 250 mF/cm² to about800 mF/cm², about 300 mF/cm² to about 400 mF/cm², about 300 mF/cm² toabout 500 mF/cm², about 300 mF/cm² to about 600 mF/cm², about 300 mF/cm²to about 700 mF/cm², about 300 mF/cm² to about 800 mF/cm², about 400mF/cm² to about 500 mF/cm², about 400 mF/cm² to about 600 mF/cm², about400 mF/cm² to about 700 mF/cm², about 400 mF/cm² to about 800 mF/cm²,about 500 mF/cm² to about 600 mF/cm², about 500 mF/cm² to about 700mF/cm², about 500 mF/cm² to about 800 mF/cm², about 600 mF/cm² to about700 mF/cm², about 600 mF/cm² to about 800 mF/cm², or about 700 mF/cm² toabout 800 mF/cm². In some embodiments, the electrode has an arealcapacitance of about 50 mF/cm², about 75 mF/cm², about 100 mF/cm², about150 mF/cm², about 200 mF/cm², about 250 mF/cm², about 300 mF/cm², about400 mF/cm², about 500 mF/cm², about 600 mF/cm², about 700 mF/cm², orabout 800 mF/cm².

In some embodiments, the electrode has a gravimetric capacitance ofabout 80 F/g to about 150 F/g. In some embodiments, the electrode has agravimetric capacitance of at least about 80 F/g. In some embodiments,the electrode has a gravimetric capacitance of at most about 150 F/g. Insome embodiments, the electrode has a gravimetric capacitance of about80 F/g to about 90 F/g, about 80 F/g to about 100 F/g, about 80 F/g toabout 110 F/g, about 80 F/g to about 120 F/g, about 80 F/g to about 130F/g, about 80 F/g to about 140 F/g, about 80 F/g to about 150 F/g, about90 F/g to about 100 F/g, about 90 F/g to about 110 F/g, about 90 F/g toabout 120 F/g, about 90 F/g to about 130 F/g, about 90 F/g to about 140F/g, about 90 F/g to about 150 F/g, about 100 F/g to about 110 F/g,about 100 F/g to about 120 F/g, about 100 F/g to about 130 F/g, about100 F/g to about 140 F/g, about 100 F/g to about 150 F/g, about 110 F/gto about 120 F/g, about 110 F/g to about 130 F/g, about 110 F/g to about140 F/g, about 110 F/g to about 150 F/g, about 120 F/g to about 130 F/g,about 120 F/g to about 140 F/g, about 120 F/g to about 150 F/g, about130 F/g to about 140 F/g, about 130 F/g to about 150 F/g, or about 140F/g to about 150 F/g. In some embodiments, the electrode has agravimetric capacitance of about 80 F/g, about 90 F/g, about 100 F/g,about 110 F/g, about 120 F/g, about 130 F/g, about 140 F/g, or about 150F/g. In some embodiments, the electrode has a packing density of about0.1 g/cm³ to about 1 g/cm³. In some embodiments, the electrode has apacking density of at least about 0.1 g/cm³. In some embodiments, theelectrode has a packing density of at most about 1 g/cm³. In someembodiments, the electrode has a packing density of about 0.1 g/cm³ toabout 0.2 g/cm³, about 0.1 g/cm³ to about 0.3 g/cm³, about 0.1 g/cm³ toabout 0.4 g/cm³, about 0.1 g/cm³ to about 0.5 g/cm³, about 0.1 g/cm³ toabout 0.6 g/cm³, about 0.1 g/cm³ to about 0.7 g/cm³, about 0.1 g/cm³ toabout 0.8 g/cm³, about 0.1 g/cm³ to about 0.9 g/cm³, about 0.1 g/cm³ toabout 1 g/cm³, about 0.2 g/cm³ to about 0.3 g/cm³, about 0.2 g/cm³ toabout 0.4 g/cm³, about 0.2 g/cm³ to about 0.5 g/cm³, about 0.2 g/cm³ toabout 0.6 g/cm³, about 0.2 g/cm³ to about 0.7 g/cm³, about 0.2 g/cm³ toabout 0.8 g/cm³, about 0.2 g/cm³ to about 0.9 g/cm³, about 0.2 g/cm³ toabout 1 g/cm³, about 0.3 g/cm³ to about 0.4 g/cm³, about 0.3 g/cm³ toabout 0.5 g/cm³, about 0.3 g/cm³ to about 0.6 g/cm³, about 0.3 g/cm³ toabout 0.7 g/cm³, about 0.3 g/cm³ to about 0.8 g/cm³, about 0.3 g/cm³ toabout 0.9 g/cm³, about 0.3 g/cm³ to about 1 g/cm³, about 0.4 g/cm³ toabout 0.5 g/cm³, about 0.4 g/cm³ to about 0.6 g/cm³, about 0.4 g/cm³ toabout 0.7 g/cm³, about 0.4 g/cm³ to about 0.8 g/cm³, about 0.4 g/cm³ toabout 0.9 g/cm³, about 0.4 g/cm³ to about 1 g/cm³, about 0.5 g/cm³ toabout 0.6 g/cm³, about 0.5 g/cm³ to about 0.7 g/cm³, about 0.5 g/cm³ toabout 0.8 g/cm³, about 0.5 g/cm³ to about 0.9 g/cm³, about 0.5 g/cm³ toabout 1 g/cm³, about 0.6 g/cm³ to about 0.7 g/cm³, about 0.6 g/cm³ toabout 0.8 g/cm³, about 0.6 g/cm³ to about 0.9 g/cm³, about 0.6 g/cm³ toabout 1 g/cm³, about 0.7 g/cm³ to about 0.8 g/cm³, about 0.7 g/cm³ toabout 0.9 g/cm³, about 0.7 g/cm³ to about 1 g/cm³, about 0.8 g/cm³ toabout 0.9 g/cm³, about 0.8 g/cm³ to about 1 g/cm³, or about 0.9 g/cm³ toabout 1 g/cm³. In some embodiments, the electrode has a packing densityof about 0.1 g/cm³, about 0.2 g/cm³, about 0.3 g/cm³, about 0.4 g/cm³,about 0.5 g/cm³, about 0.6 g/cm³, about 0.7 g/cm³, about 0.8 g/cm³,about 0.9 g/cm³, or about 1 g/cm³.

In one aspect, the present disclosure provides methods comprisingreceiving an activated carbon substrate; casting the activated carbonsubstrate on a current collector having a carbon-based coating; andgenerating a light beam having a power density to generate one or morechannels in the activated carbon substrate, thereby creating anactivated carbon-based electrode comprising one or more channels.

In some embodiments, the light beam has a wavelength of about 375nanometers to about 10,000 nanometers. In some embodiments, the lightbeam has a wavelength of at least about 375 nanometers. In someembodiments, the light beam has a wavelength of at most about 10,000nanometers. In some embodiments, the light beam has a wavelength ofabout 375 nanometers to about 470 nanometers, about 375 nanometers toabout 530 nanometers, about 375 nanometers to about 600 nanometers,about 375 nanometers to about 780 nanometers, about 375 nanometers toabout 1,000 nanometers, about 375 nanometers to about 2,000 nanometers,about 375 nanometers to about 3,000 nanometers, about 375 nanometers toabout 5,000 nanometers, about 375 nanometers to about 7,000 nanometers,about 375 nanometers to about 10,000 nanometers, about 470 nanometers toabout 530 nanometers, about 470 nanometers to about 600 nanometers,about 470 nanometers to about 780 nanometers, about 470 nanometers toabout 1,000 nanometers, about 470 nanometers to about 2,000 nanometers,about 470 nanometers to about 3,000 nanometers, about 470 nanometers toabout 5,000 nanometers, about 470 nanometers to about 7,000 nanometers,about 470 nanometers to about 10,000 nanometers, about 530 nanometers toabout 600 nanometers, about 530 nanometers to about 780 nanometers,about 530 nanometers to about 1,000 nanometers, about 530 nanometers toabout 2,000 nanometers, about 530 nanometers to about 3,000 nanometers,about 530 nanometers to about 5,000 nanometers, about 530 nanometers toabout 7,000 nanometers, about 530 nanometers to about 10,000 nanometers,about 600 nanometers to about 780 nanometers, about 600 nanometers toabout 1,000 nanometers, about 600 nanometers to about 2,000 nanometers,about 600 nanometers to about 3,000 nanometers, about 600 nanometers toabout 5,000 nanometers, about 600 nanometers to about 7,000 nanometers,about 600 nanometers to about 10,000 nanometers, about 780 nanometers toabout 1,000 nanometers, about 780 nanometers to about 2,000 nanometers,about 780 nanometers to about 3,000 nanometers, about 780 nanometers toabout 5,000 nanometers, about 780 nanometers to about 7,000 nanometers,about 780 nanometers to about 10,000 nanometers, about 1,000 nanometersto about 2,000 nanometers, about 1,000 nanometers to about 3,000nanometers, about 1,000 nanometers to about 5,000 nanometers, about1,000 nanometers to about 7,000 nanometers, about 1,000 nanometers toabout 10,000 nanometers, about 2,000 nanometers to about 3,000nanometers, about 2,000 nanometers to about 5,000 nanometers, about2,000 nanometers to about 7,000 nanometers, about 2,000 nanometers toabout 10,000 nanometers, about 3,000 nanometers to about 5,000nanometers, about 3,000 nanometers to about 7,000 nanometers, about3,000 nanometers to about 10,000 nanometers, about 5,000 nanometers toabout 7,000 nanometers, about 5,000 nanometers to about 10,000nanometers, or about 7,000 nanometers to about 10,000 nanometers. Insome embodiments, the light beam has a wavelength of about 375nanometers, about 470 nanometers, about 530 nanometers, about 600nanometers, about 780 nanometers, about 1,000 nanometers, about 2,000nanometers, about 3,000 nanometers, about 5,000 nanometers, about 7,000nanometers, or about 10,000 nanometers.

In. some embodiments, the light beam has a power density of about 0.01 Wto about 100 W. In. some embodiments, the light beam has a power densityof at least about 0.01 W. In. some embodiments, the light beam has apower density of at most about 100 W. In. some embodiments, the lightbeam has a power density of about 0.01 W to about 0.05 W, about 0.01 Wto about 0.1 W, about 0.01 W to about 0.2 W, about 0.01 W to about 0.5W, about 0.01 W to about 1 W, about 0.01 W to about 2 W, about 0.01 W toabout 5 W, about 0.01 W to about 10 W, about 0.01 W to about 20 W, about0.01 W to about 50 W, about 0.01 W to about 100 W, about 0.05 W to about0.1 W, about 0.05 W to about 0.2 W, about 0.05 W to about 0.5 W, about0.05 W to about 1 W, about 0.05 W to about 2 W, about 0.05 W to about 5W, about 0.05 W to about 10 W, about 0.05 W to about 20 W, about 0.05 Wto about 50 W, about 0.05 W to about 100 W, about 0.1 W to about 0.2 W,about 0.1 W to about 0.5 W, about 0.1 W to about 1 W, about 0.1 W toabout 2 W, about 0.1 W to about 5 W, about 0.1 W to about 10 W, about0.1 W to about 20 W, about 0.1 W to about 50 W, about 0.1 W to about 100W, about 0.2 W to about 0.5 W, about 0.2 W to about 1 W, about 0.2 W toabout 2 W, about 0.2 W to about 5 W, about 0.2 W to about 10 W, about0.2 W to about 20 W, about 0.2 W to about 50 W, about 0.2 W to about 100W, about 0.5 W to about 1 W, about 0.5 W to about 2 W, about 0.5 W toabout 5 W, about 0.5 W to about 10 W, about 0.5 W to about 20 W, about0.5 W to about 50 W, about 0.5 W to about 100 W, about 1 W to about 2 W,about 1 W to about 5 W, about 1 W to about 10 W, about 1 W to about 20W, about 1 W to about 50 W, about 1 W to about 100 W, about 2 W to about5 W, about 2 W to about 10 W, about 2 W to about 20 W, about 2 W toabout 50 W, about 2 W to about 100 W, about 5 W to about 10 W, about 5 Wto about 20 W, about 5 W to about 50 W, about 5 W to about 100 W, about10 W to about 20 W, about 10 W to about 50 W, about 10 W to about 100 W,about 20 W to about 50 W, about 20 W to about 100 W, or about 50 W toabout 100 W. In. some embodiments, the light beam has a power density ofabout 0.01 W, about 0.05 W, about 0.1 W, about 0.2 W, about 0.5 W, about1 W, about 2 W, about 5 W, about 10 W, about 20 W, about 50 W, or about100 W.

In some embodiments, the carbon-based coating comprises amorphouscarbon. In some embodiments, the activated carbon substrate ischemically activated, physically activated, or any combination thereof.In some embodiments, the activated carbon substrate comprises activatedcarbon, activated charcoal, activated carbon cloth, activated carbonfiber, activated glassy carbon, activated carbon nanofoam, activatedcarbon aerogel, or any combination thereof. In some embodiments, theactivated carbon substrate is activated carbon cloth. In someembodiments, the activated carbon substrate comprises carbon derivedfrom one or more coconut shells.

In some embodiments, the current collector is metallic. In someembodiments, the current collector is non-metallic. In some embodiments,the current collector comprises aluminum, nickel, copper, platinum,iron, steel, graphite, carbon cloth, or combinations thereof. In someembodiments, the current collector comprises aluminum.

In some embodiments, the one or more channels have a pore size fromabout 50 nanometers to about 500 micrometers. In some embodiments, theone or more channels have a pore size of about 100 micrometers. In someembodiments, the one or more channels have a pore size of at least about50 nanometers. In some embodiments, the one or more channels have a poresize of at most about 500 micrometers.

In some embodiments, the activated carbon-based electrode has an arealcapacitance of about 50 mF/cm² to about 800 mF/cm². In some embodiments,the activated carbon-based electrode has an areal capacitance of atleast about 50 mF/cm². In some embodiments, the activated carbon-basedelectrode has an areal capacitance of at most about 800 mF/cm². In someembodiments, the activated carbon-based electrode has a gravimetriccapacitance of about 80 F/g to about 150 F/g. In some embodiments, theactivated carbon-based electrode has a gravimetric capacitance of atleast about 80 F/g. In some embodiments, the activated carbon-basedelectrode has a gravimetric capacitance of at most about 150 F/g.

In some embodiments, the activated carbon-based electrode has a packingdensity of about 0.1 g/cm³ to 1.0 g/cm³. In some embodiments, theactivated carbon-based electrode has a packing density of at least about0.1 g/cm³. In some embodiments, the activated carbon-based electrode hasa packing density of at most about 1.0 g/cm³. In some embodiments, theactivated carbon-based electrode has a packing density of about 0.5g/cm³.

In one aspect, the present disclosure provides a supercapacitorcomprising a first electrode, a second electrode, and an electrolyte,wherein at least the first electrode or the second electrode comprises acurrent collector and an activated carbon substrate.

In some embodiments, the current collector comprises a carbon substrate.In some embodiments, the carbon substrate comprises amorphous carbon. Insome embodiments, the activated carbon substrate is chemicallyactivated, physically activated, or any combination thereof. In someembodiments, the activated carbon substrate comprises activated carbon,activated charcoal, activated carbon cloth, activated carbon fiber,activated glassy carbon, activated carbon nanofoam, activated carbonaerogel, or any combination thereof. In some embodiments, the activatedcarbon substrate is activated carbon cloth. In some embodiments, theactivated carbon substrate comprises carbon derived from one or morecoconut shells.

In some embodiments, the current collector is metallic. In someembodiments, the current collector is non-metallic. In some embodiments,the current collector comprises aluminum, nickel, copper, platinum,iron, steel, graphite, carbon cloth, or combinations thereof. In someembodiments, the current collector comprises aluminum.

In some embodiments, at least one of the first electrode and the secondelectrode comprises one or more channels. In some embodiments, the oneor more channels have a pore size from about 50 nanometers to about 500micrometers. In some embodiments, the one or more channels have a poresize of about 100 micrometers. In some embodiments, the one or morechannels have a pore size of at least about 50 nanometers. In someembodiments, the one or more channels have a pore size of at most about500 micrometers.

In some embodiments, the supercapacitor has an areal capacitance ofabout 50 mF/cm² to about 800 mF/cm². In some embodiments, thesupercapacitor has an areal capacitance of at least about 50 mF/cm². Insome embodiments, the supercapacitor has an areal capacitance of at mostabout 800 mF/cm². In some embodiments, the supercapacitor has agravimetric capacitance of about 80 F/g to about 150 F/g. In someembodiments, the supercapacitor has a gravimetric capacitance of atleast about 80 F/g. In some embodiments, the supercapacitor has agravimetric capacitance of at most about 150 F/g.

In some embodiments, the electrolyte is aqueous. In some embodiments,the electrolyte comprises tetraethylammonium tetrafluoroborate (TEABF₄)in acetonitrile. In some embodiments, the electrolyte comprises fromabout 0.1M to about 1.5 M tetraethylammonium tetrafluoroborate (TEABF₄)in acetonitrile. In some embodiments, the electrolyte comprises about 1M tetraethylammonium tetrafluoroborate (TEABF₄) in acetonitrile.

In some embodiments, the electrolyte is non-aqueous. In someembodiments, the electrolyte comprises one or more ionic liquids. Insome embodiments, the one or more ionic liquids are in a pure form orare dissolved in a solvent. In some embodiments, the solvent isacetonitrile. In some embodiments, the electrolyte comprises1-Allyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide,1-Ethyl-3-methylimidazolium tetrafluoroborate,1-Butyl-3-methylimidazolium tetrafluoroborate,1-Hexyl-3-methylimidazolium bis(trifluormethylsulfonyl)imide,1-Butyl-3-methylimidazolium trifluoromethanesulfonate,1-Ethyl-3-methylimidazolium 1,1,2,2-tetrafluoroethanesulfonate,1-Ethyl-3-methylimidazolium trifluoromethanesulfonate,1-Ethyl-3-methylimidazolium diethyl phosphate, or any combinationthereof.

In one aspect, the present disclosure provides an electrolyte comprisingan oxidizing agent, a reducing agent, and an aqueous solution. In someembodiments, the oxidizing agent and the reducing agent comprise a redoxcouple. In some embodiments, the redox couple comprises fluorine,manganese, chlorine, chromium, oxygen, silver, iron, iodine, copper,tin, quinone, bromine, iodine, vanadium, or combinations thereof. Insome embodiments, the redox couple comprises potassium ferrocyanide,hydroquinone, vanadyly sulfate, p-phenylenediamine, p-phenylenediimine,potassium iodide, potassium bromide, copper chloride, hydroquinone,copper sulfate, heptylviologen dibromide, methyl viologen bromide, orany combination thereof. In some embodiments, the redox couple comprisesferric cations. In some embodiments, the redox couple comprises Fe(CN)₆³⁻/Fe(CN)₆ ⁴⁻.

In some embodiments, the aqueous solution comprises sulfate ions. Insome embodiments, the aqueous solution comprises sodium ions. In someembodiments, the aqueous solution comprises Na₂SO₄.

In some embodiments, the electrolyte comprises Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻ andNa₂SO₄. In some embodiments, the electrolyte comprises about 1 M Na₂SO₄.In some embodiments, the electrolyte comprises about 0.01 M to about 1.0M of Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻. In some embodiments, the electrolytecomprises about 0.025 M Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻ and about 1.0 M Na₂SO₄. Insome embodiments, the electrolyte comprises about 0.050M Fe(CN)₆³⁻/Fe(CN)₆ ⁴⁻ and about 1.0 M Na₂SO₄. In some embodiments, theelectrolyte comprises about 0.100 M Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻ and about 1.0M Na₂SO₄. In some embodiments, the electrolyte comprises about 0.200 MFe(CN)₆ ³⁻/Fe(CN)₆ ⁴ and about 1.0 M Na₂SO₄.

In one aspect, the present disclosure provides a supercapacitorcomprising a first electrode, a second electrode, and an electrolyte. Insome embodiments, the electrolyte comprises an oxidizing agent, areducing agent, and an aqueous solution. In some embodiments, theoxidizing agent and the reducing agent comprise a redox couple. In someembodiments, the redox couple comprises fluorine, manganese, chlorine,chromium, oxygen, silver, iron, iodine, copper, tin, quinone, bromine,iodine, vanadium, or combinations thereof. In some embodiments, theredox couple comprises potassium ferrocyanide, hydroquinone, vanadylysulfate, p-phenylenediamine, p-phenylenediimine, potassium iodide,potassium bromide, copper chloride, hydroquinone, copper sulfate,heptylviologen dibromidemethyl viologen bromide, or any combinationthereof. In some embodiments, the redox couple comprises ferric cations.In some embodiments, the redox couple comprises Fe(CN)₆ ³⁻ /Fe(CN)₆ ⁴⁻.

In some embodiments, the aqueous solution comprises sulfate ions. Insome embodiments, the aqueous solution comprises sodium ions. In someembodiments, the aqueous solution comprises Na₂SO₄.

In some embodiments, the electrolyte comprises Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻ andNa₂SO₄. In some embodiments, the electrolyte comprises about 1 M Na₂SO₄.In some embodiments, electrolyte comprises about 0.01 M to about 1.0 Mof Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻. In some embodiments, the electrolyte comprisesabout 0.025 M Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻ and about 1.0 M Na₂SO₄. In someembodiments, the electrolyte comprises about 0.050 M Fe(CN)₆ ³⁻/Fe(CN)₆⁴⁻ and about 1.0 M Na₂SO₄. In some embodiments, the electrolytecomprises about 0.100 M Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻ and about 1.0 M Na₂SO₄. Insome embodiments, the electrolyte comprises about 0.200 M Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻ and about 1.0 M Na₂SO₄.

In some embodiments, the supercapacitor has an areal capacitance ofabout 105 mF/cm² to about 335 mF/cm². In some embodiments, thesupercapacitor has an areal capacitance of at least about 105 mF/cm². Insome embodiments, the supercapacitor has an areal capacitance of at mostabout 335 mF/cm². In some embodiments, the supercapacitor has an arealcapacitance of about 105 mF/cm² to about 125 mF/cm², about 105 mF/cm² toabout 150 mF/cm², about 105 mF/cm² to about 175 mF/cm², about 105 mF/cm²to about 200 mF/cm², about 105 mF/cm² to about 225 mF/cm², about 105mF/cm² to about 250 mF/cm², about 105 mF/cm² to about 275 mF/cm², about105 mF/cm² to about 300 mF/cm², about 105 mF/cm² to about 335 mF/cm²,about 125 mF/cm² to about 150 mF/cm², about 125 mF/cm² to about 175mF/cm², about 125 mF/cm² to about 200 mF/cm², about 125 mF/cm² to about225 mF/cm², about 125 mF/cm² to about 250 mF/cm², about 125 mF/cm² toabout 275 mF/cm², about 125 mF/cm² to about 300 mF/cm², about 125 mF/cm²to about 335 mF/cm², about 150 mF/cm² to about 175 mF/cm², about 150mF/cm² to about 200 mF/cm², about 150 mF/cm² to about 225 mF/cm², about150 mF/cm² to about 250 mF/cm², about 150 mF/cm² to about 275 mF/cm²,about 150 mF/cm² to about 300 mF/cm², about 150 mF/cm² to about 335mF/cm², about 175 mF/cm² to about 200 mF/cm², about 175 mF/cm² to about225 mF/cm², about 175 mF/cm² to about 250 mF/cm², about 175 mF/cm² toabout 275 mF/cm², about 175 mF/cm² to about 300 mF/cm², about 175 mF/cm²to about 335 mF/cm², about 200 mF/cm² to about 225 mF/cm², about 200mF/cm² to about 250 mF/cm², about 200 mF/cm² to about 275 mF/cm², about200 mF/cm² to about 300 mF/cm², about 200 mF/cm² to about 335 mF/cm²,about 225 mF/cm² to about 250 mF/cm², about 225 mF/cm² to about 275mF/cm², about 225 mF/cm² to about 300 mF/cm², about 225 mF/cm² to about335 mF/cm², about 250 mF/cm² to about 275 mF/cm², about 250 mF/cm² toabout 300 mF/cm², about 250 mF/cm² to about 335 mF/cm², about 275 mF/cm²to about 300 mF/cm², about 275 mF/cm² to about 335 mF/cm², or about 300mF/cm² to about 335 mF/cm². In some embodiments, the supercapacitor hasan areal capacitance of about 105 mF/cm², about 125 mF/cm², about 150mF/cm², about 175 mF/cm², about 200 mF/cm², about 225 mF/cm², about 250mF/cm², about 275 mF/cm², about 300 mF/cm², or about 335 mF/cm².

In some embodiments, the supercapacitor has a columbic efficiency ofabout 58% to about 98%. In some embodiments, the supercapacitor has acolumbic efficiency of at least about 58%. In some embodiments, thesupercapacitor has a columbic efficiency of at most about 98%. In someembodiments, the supercapacitor has a columbic efficiency of about 58%to about 60%, about 58% to about 65%, about 58% to about 70%, about 58%to about 75%, about 58% to about 80%, about 58% to about 85%, about 58%to about 90%, about 58% to about 95%, about 58% to about 98%, about 60%to about 65%, about 60% to about 70%, about 60% to about 75%, about 60%to about 80%, about 60% to about 85%, about 60% to about 90%, about 60%to about 95%, about 60% to about 98%, about 65% to about 70%, about 65%to about 75%, about 65% to about 80%, about 65% to about 85%, about 65%to about 90%, about 65% to about 95%, about 65% to about 98%, about 70%to about 75%, about 70% to about 80%, about 70% to about 85%, about 70%to about 90%, about 70% to about 95%, about 70% to about 98%, about 75%to about 80%, about 75% to about 85%, about 75% to about 90%, about 75%to about 95%, about 75% to about 98%, about 80% to about 85%, about 80%to about 90%, about 80% to about 95%, about 80% to about 98%, about 85%to about 90%, about 85% to about 95%, about 85% to about 98%, about 90%to about 95%, about 90% to about 98%, or about 95% to about 98%. In someembodiments, the supercapacitor has a columbic efficiency of about 58%,about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about90%, about 95%, or about 98%.

In some embodiments, the supercapacitor has a gravimetric capacitance ofabout 80 F/g to about 150 F/g. In some embodiments, the supercapacitorhas a gravimetric capacitance of at least about 80 F/g. In someembodiments, the supercapacitor has a gravimetric capacitance of at mostabout 150 F/g. In some embodiments, the supercapacitor has a gravimetriccapacitance of about 80 F/g to about 90 F/g, about 80 F/g to about 100F/g, about 80 F/g to about 110 F/g, about 80 F/g to about 120 F/g, about80 F/g to about 130 F/g, about 80 F/g to about 140 F/g, about 80 F/g toabout 150 F/g, about 90 F/g to about 100 F/g, about 90 F/g to about 110F/g, about 90 F/g to about 120 F/g, about 90 F/g to about 130 F/g, about90 F/g to about 140 F/g, about 90 F/g to about 150 F/g, about 100 F/g toabout 110 F/g, about 100 F/g to about 120 F/g, about 100 F/g to about130 F/g, about 100 F/g to about 140 F/g, about 100 F/g to about 150 F/g,about 110 F/g to about 120 F/g, about 110 F/g to about 130 F/g, about110 F/g to about 140 F/g, about 110 F/g to about 150 F/g, about 120 F/gto about 130 F/g, about 120 F/g to about 140 F/g, about 120 F/g to about150 F/g, about 130 F/g to about 140 F/g, about 130 F/g to about 150 F/g,or about 140 F/g to about 150 F/g. In some embodiments, thesupercapacitor has a gravimetric capacitance of about 80 F/g, about 90F/g, about 100 F/g, about 110 F/g, about 120 F/g, about 130 F/g, about140 F/g, or about 150 F/g.

In one aspect, the present disclosure presents a supercapacitorcomprising a first electrode, a second electrode, and an electrolyte,wherein at least the first electrode or the second electrode comprises acurrent collector and an activated carbon substrate. In someembodiments, the current collector comprises a carbon substrate. In someembodiments, the carbon substrate comprises amorphous carbon.

In some embodiments, the activated carbon substrate is chemicallyactivated, physically activated, or any combination thereof. In someembodiments, the activated carbon substrate comprises activated carbon,activated charcoal, activated carbon cloth, activated carbon fiber,activated glassy carbon, activated carbon nanofoam, activated carbonaerogel, or combinations thereof. In some embodiments, the activatedcarbon substrate is activated carbon cloth. In some embodiments, theactivated carbon substrate comprises carbon derived from one or morecoconut shells.

In some embodiments, the current collector is metallic. In someembodiments, the current collector is non-metallic. In some embodiments,the current collector comprises aluminum, nickel, copper, platinum,iron, steel, graphite, carbon cloth, or combinations thereof. In someembodiments, the current collector comprises aluminum.

In some embodiments, at least the first electrode or second electrodecomprises one or more channels. In some embodiments, the one or morechannels have a pore size from about 50 nanometers to about 500micrometers. In some embodiments, the one or more channels have a poresize of about 100 micrometers. In some embodiments, the one or morechannels have a pore size of at least about 50 nanometers. In someembodiments, the one or more channels have a pore size of at most about500 micrometers.

In some embodiments, the electrolyte comprises an oxidizing agent, areducing agent, and an aqueous solution. In some embodiments, theoxidizing agent and the reducing agent comprise a redox couple. In someembodiments, the redox couple comprises fluorine, manganese, chlorine,chromium, oxygen, silver, iron, iodine, copper, tin, quinone, bromine,iodine, vanadium, or combinations thereof. In some embodiments, theredox couple comprises potassium ferrocyanide, hydroquinone, vanadylysulfate, p-phenylenediamine, p-phenylenediimine, potassium iodide,potassium bromide, copper chloride, hydroquinone, copper sulfate,heptylviologen dibromidemethyl viologen bromide, or any combinationthereof. In some embodiments, the redox couple comprises ferric cations.In some embodiments, the redox couple comprises Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻.

In some embodiments, the aqueous solution comprises sulfate ions. Insome embodiments, the aqueous solution comprises sodium ions. In someembodiments, the aqueous solution comprises Na₂SO₄.

In some embodiments, the electrolyte comprises Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻ andNa₂SO₄. In some embodiments, the electrolyte comprises about 1 M Na₂SO₄.In some embodiments, the electrolyte comprises about 0.01 M to about 1.0M of Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻. In some embodiments, the electrolytecomprises about 0.025 M Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻ and about 1.0 M Na₂SO₄. Insome embodiments, the electrolyte comprises about 0.050 M Fe(CN)₆³⁻/Fe(CN)₆ ⁴⁻ and about 1.0 M Na₂SO₄. In some embodiments, theelectrolyte comprises about 0.100 M Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻ and about 1.0M Na₂SO₄. In some embodiments, the electrolyte comprises about 0.200 MFe(CN)₆ ³⁻ /Fe(CN)₆ ⁴⁻ and about 1.0 M Na₂SO₄.

In some embodiments, the supercapacitor has an areal capacitance ofabout 360 mF/cm² to about 380 mF/cm².

In some embodiments, the supercapacitor has a volumetric energy densityof about 0.5 mWh/cm³ to about 6 mWh/cm³. In some embodiments, thesupercapacitor has a volumetric energy density of at least about 0.5mWh/cm³. In some embodiments, the supercapacitor has a volumetric energydensity of at most about 6 mWh/cm³. In some embodiments, thesupercapacitor has a volumetric energy density of about 0.5 mWh/cm³ toabout 1 mWh/cm³, about 0.5 mWh/cm³ to about 1.5 mWh/cm³, about 0.5mWh/cm³ to about 2 mWh/cm³, about 0.5 mWh/cm³ to about 2.5 mWh/cm³,about 0.5 mWh/cm³ to about 3 mWh/cm³, about 0.5 mWh/cm³ to about 3.5mWh/cm³, about 0.5 mWh/cm³ to about 4 mWh/cm³, about 0.5 mWh/cm³ toabout 4.5 mWh/cm³, about 0.5 mWh/cm³ to about 5 mWh/cm³, about 0.5mWh/cm³ to about 5.5 mWh/cm³, about 0.5 mWh/cm³ to about 6 mWh/cm³,about 1 mWh/cm³ to about 1.5 mWh/cm³, about 1 mWh/cm³ to about 2mWh/cm³, about 1 mWh/cm³ to about 2.5 mWh/cm³, about 1 mWh/cm³ to about3 mWh/cm³, about 1 mWh/cm³ to about 3.5 mWh/cm³, about 1 mWh/cm³ toabout 4 mWh/cm³, about 1 mWh/cm³ to about 4.5 mWh/cm³, about 1 mWh/cm³to about 5 mWh/cm³, about 1 mWh/cm³ to about 5.5 mWh/cm³, about 1mWh/cm³ to about 6 mWh/cm³, about 1.5 mWh/cm³ to about 2 mWh/cm³, about1.5 mWh/cm³ to about 2.5 mWh/cm³, about 1.5 mWh/cm³ to about 3 mWh/cm³,about 1.5 mWh/cm³ to about 3.5 mWh/cm³, about 1.5 mWh/cm³ to about 4mWh/cm³, about 1.5 mWh/cm³ to about 4.5 mWh/cm³, about 1.5 mWh/cm³ toabout 5 mWh/cm³, about 1.5 mWh/cm³ to about 5.5 mWh/cm³, about 1.5mWh/cm³ to about 6 mWh/cm³, about 2 mWh/cm³ to about 2.5 mWh/cm³, about2 mWh/cm³ to about 3 mWh/cm³, about 2 mWh/cm³ to about 3.5 mWh/cm³,about 2 mWh/cm³ to about 4 mWh/cm³, about 2 mWh/cm³ to about 4.5mWh/cm³, about 2 mWh/cm³ to about 5 mWh/cm³, about 2 mWh/cm³ to about5.5 mWh/cm³, about 2 mWh/cm³ to about 6 mWh/cm³, about 2.5 mWh/cm³ toabout 3 mWh/cm³, about 2.5 mWh/cm³ to about 3.5 mWh/cm³, about 2.5mWh/cm³ to about 4 mWh/cm³, about 2.5 mWh/cm³ to about 4.5 mWh/cm³,about 2.5 mWh/cm³ to about 5 mWh/cm³, about 2.5 mWh/cm³ to about 5.5mWh/cm³, about 2.5 mWh/cm³ to about 6 mWh/cm³, about 3 mWh/cm³ to about3.5 mWh/cm³, about 3 mWh/cm³ to about 4 mWh/cm³, about 3 mWh/cm³ toabout 4.5 mWh/cm³, about 3 mWh/cm³ to about 5 mWh/cm³, about 3 mWh/cm³to about 5.5 mWh/cm³, about 3 mWh/cm³ to about 6 mWh/cm³, about 3.5mWh/cm³ to about 4 mWh/cm³, about 3.5 mWh/cm³ to about 4.5 mWh/cm³,about 3.5 mWh/cm³ to about 5 mWh/cm³, about 3.5 mWh/cm³ to about 5.5mWh/cm³, about 3.5 mWh/cm³ to about 6 mWh/cm³, about 4 mWh/cm³ to about4.5 mWh/cm³, about 4 mWh/cm³ to about 5 mWh/cm³, about 4 mWh/cm³ toabout 5.5 mWh/cm³, about 4 mWh/cm³ to about 6 mWh/cm³, about 4.5 mWh/cm³to about 5 mWh/cm³, about 4.5 mWh/cm³ to about 5.5 mWh/cm³, about 4.5mWh/cm³ to about 6 mWh/cm³, about 5 mWh/cm³ to about 5.5 mWh/cm³, about5 mWh/cm³ to about 6 mWh/cm³, or about 5.5 mWh/cm³ to about 6 mWh/cm³.In some embodiments, the supercapacitor has a volumetric energy densityof about 0.5 mWh/cm³, about 1 mWh/cm³, about 1.5 mWh/cm³, about 2mWh/cm³, about 2.5 mWh/cm³, about 3 mWh/cm³, about 3.5 mWh/cm³, about 4mWh/cm³, about 4.5 mWh/cm³, about 5 mWh/cm³, about 5.5 mWh/cm³, or about6 mWh/cm³.

In some embodiments, the supercapacitor has a power density of about 1W/cm³ to about 6 W/cm³. In some embodiments, the supercapacitor has apower density of at least about 1 W/cm³. In some embodiments, thesupercapacitor has a power density of at most about 6 W/cm³. In someembodiments, the supercapacitor has a power density of about 1 W/cm³ toabout 1.5 W/cm³, about 1 W/cm³ to about 2 W/cm³, about 1 W/cm³ to about2.5 W/cm³, about 1 W/cm³ to about 3 W/cm³, about 1 W/cm³ to about 3.5W/cm³, about 1 W/cm³ to about 4 W/cm³, about 1 W/cm³ to about 4.5 W/cm³,about 1 W/cm³ to about 5 W/cm³, about 1 W/cm³ to about 5.5 W/cm³, about1 W/cm³ to about 6 W/cm³, about 1.5 W/cm³ to about 2 W/cm³, about 1.5W/cm³ to about 2.5 W/cm³, about 1.5 W/cm³ to about 3 W/cm³, about 1.5W/cm³ to about 3.5 W/cm³, about 1.5 W/cm³ to about 4 W/cm³, about 1.5W/cm³ to about 4.5 W/cm³, about 1.5 W/cm³ to about 5 W/cm³, about 1.5W/cm³ to about 5.5 W/cm³, about 1.5 W/cm³ to about 6 W/cm³, about 2W/cm³ to about 2.5 W/cm³, about 2 W/cm³ to about 3 W/cm³, about 2 W/cm³to about 3.5 W/cm³, about 2 W/cm³ to about 4 W/cm³, about 2 W/cm³ toabout 4.5 W/cm³, about 2 W/cm³ to about 5 W/cm³, about 2 W/cm³ to about5.5 W/cm³, about 2 W/cm³ to about 6 W/cm³, about 2.5 W/cm³ to about 3W/cm³, about 2.5 W/cm³ to about 3.5 W/cm³, about 2.5 W/cm³ to about 4W/cm³, about 2.5 W/cm³ to about 4.5 W/cm³, about 2.5 W/cm³ to about 5W/cm³, about 2.5 W/cm³ to about 5.5 W/cm³, about 2.5 W/cm³ to about 6W/cm³, about 3 W/cm³ to about 3.5 W/cm³, about 3 W/cm³ to about 4 W/cm³,about 3 W/cm³ to about 4.5 W/cm³, about 3 W/cm³ to about 5 W/cm³, about3 W/cm³ to about 5.5 W/cm³, about 3 W/cm³ to about 6 W/cm³, about 3.5W/cm³ to about 4 W/cm³, about 3.5 W/cm³ to about 4.5 W/cm³, about 3.5W/cm³ to about 5 W/cm³, about 3.5 W/cm³ to about 5.5 W/cm³, about 3.5W/cm³ to about 6 W/cm³, about 4 W/cm³ to about 4.5 W/cm³, about 4 W/cm³to about 5 W/cm³, about 4 W/cm³ to about 5.5 W/cm³, about 4 W/cm³ toabout 6 W/cm³, about 4.5 W/cm³ to about 5 W/cm³, about 4.5 W/cm³ toabout 5.5 W/cm³, about 4.5 W/cm³ to about 6 W/cm³, about 5 W/cm³ toabout 5.5 W/cm³, about 5 W/cm³ to about 6 W/cm³, or about 5.5 W/cm³ toabout 6 W/cm³. In some embodiments, the supercapacitor has a powerdensity of about 1 W/cm³, about 1.5 W/cm³, about 2 W/cm³, about 2.5W/cm³, about 3 W/cm³, about 3.5 W/cm³, about 4 W/cm³, about 4.5 W/cm³,about 5 W/cm³, about 5.5 W/cm³, or about 6 W/cm³.

In some embodiments, the supercapacitor has a gravimetric energy densityof about 18 Wh/kg to about 21 Wh/kg. In some embodiments, thesupercapacitor has a gravimetric energy density of at least about 18Wh/kg. In some embodiments, the supercapacitor has a gravimetric energydensity of at most about 21 Wh/kg. In some embodiments, thesupercapacitor has a gravimetric energy density of about 18 Wh/kg toabout 18.5 Wh/kg, about 18 Wh/kg to about 19 Wh/kg, about 18 Wh/kg toabout 19.5 Wh/kg, about 18 Wh/kg to about 20 Wh/kg, about 18 Wh/kg toabout 20.5 Wh/kg, about 18 Wh/kg to about 21 Wh/kg, about 18.5 Wh/kg toabout 19 Wh/kg, about 18.5 Wh/kg to about 19.5 Wh/kg, about 18.5 Wh/kgto about 20 Wh/kg, about 18.5 Wh/kg to about 20.5 Wh/kg, about 18.5Wh/kg to about 21 Wh/kg, about 19 Wh/kg to about 19.5 Wh/kg, about 19Wh/kg to about 20 Wh/kg, about 19 Wh/kg to about 20.5 Wh/kg, about 19Wh/kg to about 21 Wh/kg, about 19.5 Wh/kg to about 20 Wh/kg, about 19.5Wh/kg to about 20.5 Wh/kg, about 19.5 Wh/kg to about 21 Wh/kg, about 20Wh/kg to about 20.5 Wh/kg, about 20 Wh/kg to about 21 Wh/kg, or about20.5 Wh/kg to about 21 Wh/kg. In some embodiments, the supercapacitorhas a gravimetric energy density of about 18 Wh/kg, about 18.5 Wh/kg,about 19 Wh/kg, about 19.5 Wh/kg, about 20 Wh/kg, about 20.5 Wh/kg, orabout 21 Wh/kg.

In some embodiments, the supercapacitor has a power density of about3,000 W/kg to about 12,000 W/kg. In some embodiments, the supercapacitorhas a power density of at least about 3,000 W/kg. In some embodiments,the supercapacitor has a power density of at most about 12,000 W/kg. Insome embodiments, the supercapacitor has a power density of about 3,000W/kg to about 4,000 W/kg, about 3,000 W/kg to about 5,000 W/kg, about3,000 W/kg to about 6,000 W/kg, about 3,000 W/kg to about 7,000 W/kg,about 3,000 W/kg to about 8,000 W/kg, about 3,000 W/kg to about 9,000W/kg, about 3,000 W/kg to about 10,000 W/kg, about 3,000 W/kg to about11,000 W/kg, about 3,000 W/kg to about 12,000 W/kg, about 4,000 W/kg toabout 5,000 W/kg, about 4,000 W/kg to about 6,000 W/kg, about 4,000 W/kgto about 7,000 W/kg, about 4,000 W/kg to about 8,000 W/kg, about 4,000W/kg to about 9,000 W/kg, about 4,000 W/kg to about 10,000 W/kg, about4,000 W/kg to about 11,000 W/kg, about 4,000 W/kg to about 12,000 W/kg,about 5,000 W/kg to about 6,000 W/kg, about 5,000 W/kg to about 7,000W/kg, about 5,000 W/kg to about 8,000 W/kg, about 5,000 W/kg to about9,000 W/kg, about 5,000 W/kg to about 10,000 W/kg, about 5,000 W/kg toabout 11,000 W/kg, about 5,000 W/kg to about 12,000 W/kg, about 6,000W/kg to about 7,000 W/kg, about 6,000 W/kg to about 8,000 W/kg, about6,000 W/kg to about 9,000 W/kg, about 6,000 W/kg to about 10,000 W/kg,about 6,000 W/kg to about 11,000 W/kg, about 6,000 W/kg to about 12,000W/kg, about 7,000 W/kg to about 8,000 W/kg, about 7,000 W/kg to about9,000 W/kg, about 7,000 W/kg to about 10,000 W/kg, about 7,000 W/kg toabout 11,000 W/kg, about 7,000 W/kg to about 12,000 W/kg, about 8,000W/kg to about 9,000 W/kg, about 8,000 W/kg to about 10,000 W/kg, about8,000 W/kg to about 11,000 W/kg, about 8,000 W/kg to about 12,000 W/kg,about 9,000 W/kg to about 10,000 W/kg, about 9,000 W/kg to about 11,000W/kg, about 9,000 W/kg to about 12,000 W/kg, about 10,000 W/kg to about11,000 W/kg, about 10,000 W/kg to about 12,000 W/kg, or about 11,000W/kg to about 12,000 W/kg. In some embodiments, the supercapacitor has apower density of about 3,000 W/kg, about 4,000 W/kg, about 5,000 W/kg,about 6,000 W/kg, about 7,000 W/kg, about 8,000 W/kg, about 9,000 W/kg,about 10,000 W/kg, about 11,000 W/kg, or about 12,000 W/kg.

In some embodiments, the supercapacitor has capacity retention after7,000 cycles of about 30% to about 80%. In some embodiments, thesupercapacitor has capacity retention after 7,000 cycles of at leastabout 30%. In some embodiments, the supercapacitor has capacityretention after 7,000 cycles of at most about 80%. In some embodiments,the supercapacitor has capacity retention after 7,000 cycles of about80% to about 75%, about 80% to about 70%, about 80% to about 65%, about80% to about 60%, about 80% to about 55%, about 80% to about 50%, about80% to about 45%, about 80% to about 40%, about 80% to about 35%, about80% to about 30%, about 75% to about 70%, about 75% to about 65%, about75% to about 60%, about 75% to about 55%, about 75% to about 50%, about75% to about 45%, about 75% to about 40%, about 75% to about 35%, about75% to about 30%, about 70% to about 65%, about 70% to about 60%, about70% to about 55%, about 70% to about 50%, about 70% to about 45%, about70% to about 40%, about 70% to about 35%, about 70% to about 30%, about65% to about 60%, about 65% to about 55%, about 65% to about 50%, about65% to about 45%, about 65% to about 40%, about 65% to about 35%, about65% to about 30%, about 60% to about 55%, about 60% to about 50%, about60% to about 45%, about 60% to about 40%, about 60% to about 35%, about60% to about 30%, about 55% to about 50%, about 55% to about 45%, about55% to about 40%, about 55% to about 35%, about 55% to about 30%, about50% to about 45%, about 50% to about 40%, about 50% to about 35%, about50% to about 30%, about 45% to about 40%, about 45% to about 35%, about45% to about 30%, about 40% to about 35%, about 40% to about 30%, orabout 35% to about 30%. In some embodiments, the supercapacitor hascapacity retention after 7,000 cycles of about 80%, about 75%, about70%, about 65%, about 60%, about 55%, about 50%, about 45%, about 40%,about 35%, or about 30%.

In another aspect, the present disclosure provides processes, methods,protocols and the like for manufacturing high energy storage devices,such as supercapacitors comprising at least one laser-scribed activatedcarbon electrode. In further embodiments, the supercapacitor comprisesredox active electrolytes. In some embodiments, the use of redox activeelectrolytes increases the capacitance of the high energy storagedevices. In certain embodiments, the increase in the capacitance of thehigh energy storage devices reduces the cost of the high energy storagedevice.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings or figures (also “FIG.” and “FIGs.” herein), ofwhich:

FIG. 1A provides an exemplary design and structure of laser scribedactivated carbon (LSAC) electrodes, in accordance with some embodiments.This schematic illustration shows the fabrication process of lasermodified activated carbon (LAC) electrodes. The laser treated electrodescontain trenches that serve as electrolyte reservoirs, enabling betterinteraction between the electrolyte ions and the electrode surfaces. Insome embodiments, the fabrication process comprises receiving anactivated carbon substrate; casting the activated carbon substrate on acurrent collector having a carbon-based coating; generating a light beamhaving a power density to generate one or more channels in the activatedcarbon substrate, thereby creating an activated carbon-based electrodecomprising one or more channels.

FIG. 1B is an overview SEM image showing activated carbon beforeexposure to the laser.

FIG. 1C is an SEM image showing the ˜100 μm patterns on activated carbonelectrode after exposure to 7-W laser.

FIG. 1D is a magnified view illustrating that some parts of activatedcarbon particles are etched out by laser leading to macroporousstructure.

FIG. 2A provides an exemplary optical microscope image before laserscribing showing the microstructure of an as-made LSAC electrodeprocessed from PVDF binder.

FIG. 2B provides an exemplary optical microscope image after laserscribing showing the microstructure of an LSAC electrode processed fromPVDF binder. The results reveal the appearance of macro-pores in thestructure of the electrode following the laser treatment.

FIG. 2C provides an exemplary optical microscope image before laserscribing showing the microstructure of an as-made LSAC electrodeprocessed from CMC/SBR binder.

FIG. 2D provides an exemplary optical microscope image after laserscribing showing the microstructure of an LSAC electrode processed fromCMC/SBR binder. The results reveal the appearance of macro-pores in thestructure of the electrode following the laser treatment.

FIG. 3A provides cyclic voltammetry (CV) curves of LSAC supercapacitorsin a traditional 1.0 M tetraethylammonium tetrafluoroborate (TEABF4) inacetonitrile (ACN) electrolyte before (solid line) and after (dashedline) laser treatment, obtained at a scan rate of 50 mV s⁻¹. All thevalues were measure from the full cell and calculated based on theelectrode.

FIG. 3B provides exemplary CV profiles of LAC supercapacitor in atraditional 1.0 M tetraethylammonium tetrafluoroborate (TEABF4) inacetonitrile (ACN) electrolyte at different scan rates of 30, 50, 70,100, 200, and 300 mV s⁻¹. All the values were measure from the full celland calculated based on the electrode.

FIG. 3C provides exemplary charge/discharge (CC) curves of LSACsupercapacitors in a traditional 1.0 M tetraethylammoniumtetrafluoroborate (TEABF4) in acetonitrile (ACN) electrolyte atdifferent current densities 2.8, 3.4, 5.6, 8.5, 11.3, and 14.1 mA cm⁻².All the values were measure from the full cell and calculated based onthe electrode.

FIG. 3D provides the areal capacitance retention of LSAC supercapacitorsin a traditional 1.0 M tetraethylammonium tetrafluoroborate (TEABF4) inacetonitrile (ACN) electrolyte before (ACN-N) and after (ACN-S) lasertreatment as a function of the applied current density. All the valueswere measure from the full cell and calculated based on the electrode.All the values were measure from the full cell and calculated based onthe electrode.

FIG. 3E provides gravimetric capacitance retention of LSACsupercapacitors in a traditional 1.0 M tetraethylammoniumtetrafluoroborate (TEABF4) in acetonitrile (ACN) electrolyte before(ACN-N) and after (ACN-S) laser treatment as a function of the appliedcurrent density. All the values were measure from the full cell andcalculated based on the electrode.

FIG. 3F shows Nyquist plots of the LAC supercapacitor and non-scribedsupercapacitors over a frequency range of 1 MHz to 0.1 Hz.

FIG. 4 provides exemplary cyclic voltammetry of an LSAC electrode, inaccordance with some embodiments. In the embodiment, the cyclicvoltammetry (CV) is for activated carbon electrode (prepared on aluminumcurrent collector) in 1.0 M Na₂SO₄ measured at 50 mV s⁻¹ and repeatedfor 6 cycles. The device was assembled and tested in a CR 2032 coincell.

FIG. 5A shows CV curves of a high voltage supercapacitor in aredox-active aqueous electrolyte at an increasing voltage window from1.0 V to 2.0 V in 0.1 M RE at 50 mV s⁻¹. All the electrochemicalexperiments were measured in a CR2032 coin cell.

FIG. 5B shows CV curves of a high voltage supercapacitor in aredox-active aqueous electrolyte collected at increasing concentrationsof the redox additive, tested at a scan rate of 50 mVs⁻¹. All theelectrochemical experiments were measured in a CR2032 coin cell.

FIG. 5C shows the corresponding CC curves of a high voltagesupercapacitor in a redox-active aqueous electrolyte for an activatedcarbon electrode in 1 M Na₂SO₄ containing different concentrations (0,0.025, 0.050, and 0.100 M) of the redox additive collected at a currentdensity of 11.3 mA cm⁻². All the electrochemical experiments weremeasured in a CR2032 coin cell.

FIG. 5D shows the specific capacitance by area vs. current density foran activated carbon electrode in 1 M Na₂SO₄ containing differentconcentrations (0, 0.025, 0.050, and 0.100 M) of the redox additive. Allthe electrochemical experiments were measured in a CR2032 coin cell.

FIG. 5E provides exemplary CV profiles of 0.1M RE-SC at different scanrates of 30, 50, 70, 100, 200, and 300 mVs⁻¹. All the electrochemicalexperiments were measured in a CR2032 coin cell.

FIG. 5F are Nyquist plots of the 0.1 M RE aqueous electrolyte and 1.0 MTEABF₄ in ACN supercapacitors over a frequency range of 1 MHz to 0.1 Hz.All the electrochemical experiments were measured in a CR2032 coin cell.

FIG. 6A is an illustration of the charge storage mechanism in LSACelectrode using 1.0 M Na₂SO₄ electrolyte (1) in the absence, and (2) inthe presence of redox additive.

FIG. 6B shows CV profiles comparing the electrochemical performance ofactivated carbon electrodes before and after laser scribing tested intraditional 1.0 M in acetonitrile and in 0.1 M redox electrolyte, datacollected at a scan rate of 50 mVs⁻¹.

FIG. 6C shows the evolution of the electrochemical performance of LSACsupercapacitor using 0.1 M RE at different scan rates of CVs at 30, 50,70, 100, 200 and 300 mVs⁻¹.

FIG. 6D shows the CC curves corresponding to FIG. 6C at differentcurrent densities 8.5, 11.3, 14.1, 16.9, 19.8, 22.6 mA cm⁻².

FIG. 6E shows the Areal capacitance vs. current density of fourdifferent cases.

FIG. 6F are Nyquist plots comparing the performance of four differentcases.

FIG. 6G shows a Ragone plot showing the gravimetric energy density andpower density of 0.1 M RE-LSAC system and other RE-based supercapacitorsreported in the literature.

FIG. 6H is another Ragone plot comparing the volumetric energy densityand power density of the 0.1 M RE-LSAC supercapacitor with commerciallyavailable energy storage devices.

FIG. 6I shows the long-term cycling stability of 0.1 M RE-LSACsupercapacitor at 2.0 V.

FIG. 7A shows charge/discharge (CC) curves of supercapacitors with LSACelectrodes at 20 mAcm⁻² of the activated carbon supercapacitor with0.025 M, 0.050 M, 0.100 M, and 0.200 M redox-active electrolyte [Fe(CN)₆³⁻/Fe(CN)₆ ⁴⁻] in 1.0 M Na₂SO₄ electrolyte.

FIG. 7B provides the areal capacitance of device and columbic efficiencyof supercapacitors with LSAC electrodes at different concentrations ofredox-active electrolyte are listed. Values calculated based on the CCresults at 20 mA cm⁻².

FIG. 8A shows CC curves of activated carbon supercapacitor with 0.100 Mredox-active electrolyte at various current densities of 11.3, 14.1,16.9, 19.8, and 22.6 mA cm².

FIG. 8B shows the CC curves of activated carbon supercapacitor with0.100 M redox-active electrolyte for current densities of 28.2, 33.9,39.5, 45.2, and 50.8 mA cm⁻².

FIG. 9A shows the CV curves of LSAC in a redox-active electrolyte at 50mV s⁻¹.

FIG. 9B provides the galvanostatic charge/discharge (CC) curves of LSACin a redox-active electrolyte at a current density of 11.3 mA cm⁻² at anincreasing voltage window from 1.0 V to 2 V.

FIG. 9C shows CV curves of LSAC in a redox-active electrolyte at highscan rates of 500, 700, and 1000 mVs⁻¹.

FIG. 9D shows the CC curves of LSAC in a redox-active electrolyte atvarious current densities of 28.2, 33.9, 39.5, 45.2, 50.8, and 56.5mAcm⁻².

FIG. 9E provides the comparison of gravimetric capacitance per electrodefor activated carbon before and after laser scribing, with and withoutredox electrolyte, normalized by active materials (activated carbon+0.1M RE).

FIG. 9F are bode plots of the redox electrolyte-based supercapacitorsbefore and after laser scribing (i.e. RE-AC and RE-LSAC).

DETAILED DESCRIPTION

In one aspect, the present disclosure describes carbon-based electrodes.In some embodiments, the electrodes comprise a carbon-coated currentcollector. In some embodiments the carbon-coated current collectorcomprises an activated carbon substrate. In some embodiments, thecarbon-coated current collector can be laser-irradiated to form theactivated carbon substrate. In some embodiments, the carbon-basedelectrode comprising a current collector and an activated carbonsubstrate can comprise one or more micro-channels. In some embodiments,the carbon-based electrodes comprising micro-channels may exhibit a highcapacitance. In some embodiments, the carbon-based electrodes comprisingmicro-channels may exhibit a low internal resistance.

In some embodiments, the activated carbon substrate comprises chemicallyand/or physically activated carbon, carbon cloth, carbon fiber, glassycarbon, carbon nanofoam, carbon aerogel, or combinations thereof. Incertain embodiments, the activated carbon substrate comprises activatedcarbon cloth. In some embodiments, the activated carbon substrate isderived from coconut shells.

In some embodiments, the current collector is metallic. In someembodiments, the current collector comprises aluminum, nickel, copper,platinum, steel, or combinations thereof. In certain embodiments, thecurrent collector comprises aluminum.

In some embodiments, the current collector is non-metallic. In someembodiments, the current collector comprises graphite paper, carboncloth, or any combination thereof.

In some embodiments, the carbon-based electrode comprises one or morechannels. In some embodiments, the embodiments, the one or more channelshave a pore size from about 50 nanometers to about 500 micrometers. Insome embodiments, the one or more micro-channels have a pore size ofabout 100 micrometers.

In some embodiments, the carbon-based electrode can have an arealcapacitance of from about 50 mF/cm² to about 800 mF/cm². In someembodiments, the carbon-based electrode can have an areal capacitance ofat least about 50 mF/cm². In some embodiments, the carbon-basedelectrode can have an areal capacitance of at most about 800 mF/cm².

In some embodiments, the carbon-based electrode may exhibit agravimetric capacitance of from about 80 F/g to about 150 F/g. In someembodiments, the carbon-based electrode can have a gravimetriccapacitance of at least about 80 F/g. In some embodiments, thecarbon-based electrode can have a gravimetric capacitance of at mostabout 150 F/g.

In some embodiments, the carbon-based electrode may exhibit a packingdensity from about 0.1 g/cm³ to about 1.0 g/cm³. In some embodiments,the carbon-based electrode may exhibit a packing density of about 0.5g/cm³. In some embodiments, the carbon-based electrode may exhibit apacking density of about 0.6 g/cm³.

FIG. 1 provides an exemplary design, structure, and characterization oflaser scribed activated carbon (LSAC) electrodes. In this exemplaryembodiment, activated carbon electrodes with a high packing density ofabout 0.60 g cm⁻³ are fabricated on a carbon coated aluminum currentcollector using a standard doctor blade coating technique. The exposureof the electrode to a CO₂ laser results in the formation of microscalesize trenches as illustrated in FIG. 1A. FIG. 1A is a schematicillustration showing the fabrication process of laser modified activatedcarbon (LAC) electrodes. The laser treated electrodes contain trenchesthat serve as electrolyte reservoirs, enabling better interactionbetween the electrolyte ions and the electrode surfaces. FIG. 1B andFIG. 1C show the changes of the microstructure of the electrode beforeand after laser irradiation. FIG. 1B is an overview SEM image showingactivated carbon before exposure to the laser. FIG. 1C is an SEM imageshowing the ˜100 μm patterns on activated carbon electrode afterexposure to 7-W laser. Zooming into the laser treated electrode revealsthe macroporous nature of the electrode, FIG. 1D. FIG. 1D is a magnifiedview illustrating that some parts of activated carbon particles areetched out by laser leading to macroporous structure.

The results per FIGS. 1A-D were further confirmed by the opticalmicroscopy images indicating the appearance of macropores in thestructure of the electrode following laser irradiation, per FIGS. 2A-D.

The same results are obtained when processing the electrode from anorganic system with PVDF binder and aqueous system with CMC/SBR binder.This unique electrode architecture exhibits a high surface area andporous structure, allowing the electrolyte to interact with the entiresurface of the activated materials. In addition, microscale trenches mayallow for the rapid transportation of ions and may provide an ionicconnection between the interior pores of the activated carbon particlesand the external electrolyte. These trenches may also reduce thedistance over which the ions will have to move during charge anddischarge processes. An additional advantage of this technique is thatthe exemplary electrode may maintain its high packing density afterlaser irradiation (˜0.54 g cm⁻³). Therefore, the laser irradiationtechnique proposed in this work may enable the direct fabrication ofhigh power/high energy activated carbon electrodes without compromisingtheir outstanding volumetric performance. In addition, the microscaletrenches may help alleviate the strain and stress between particlesduring charge and discharge and may improve the cycling stability of thesupercapacitor.

In one aspect, the present disclosure provides high energy storagedevices, such as supercapacitors, comprising at least one LSAC electrodeand an aqueous electrolyte.

In some embodiments, the supercapacitor comprises laser scribedactivated carbon (LSAC) electrodes in a CR2032 coin cell devices and 1 Mtetraethylammonium tetrafluoroborate (TEABF₄) in acetonitrile as theelectrolyte, per FIG. 3.

FIGS. 3A-D provide exemplary evaluations of the electrochemicalperformance of laser modified activated carbon (LAC) supercapacitors ina traditional 1.0 M tetraethylammonium tetrafluoroborate (TEABF₄) inacetonitrile (ACN) electrolyte. FIG. 3A shows an exemplary cyclicvoltammetry (CV) of the LSAC electrode before and after laserirradiation. In comparison with a non-scribed electrode, the exemplaryLSAC shows an enhanced capacitance with ideal rectangular CV curve at ascan rate of 50 mV s⁻¹. This suggests the ideal electric double layercapacitance behavior. This ideal rectangular CV shape of the exemplaryLSAC supercapacitor is retained even when tested at high scan rates upto 300 mV s⁻¹ as shown in FIG. 3B. FIG. 3B provides exemplary CVprofiles of LAC supercapacitor at different scan rates of 30, 50, 70,100, 200, and 300 mV s⁻¹. In addition, FIG. 3C shows that the exemplarydevice can maintain ideal triangular charge/discharge (CC) curves withvery small IR drop at increasing current densities. FIG. 3C providesexemplary charge/discharge (CC) curves at different current densities2.8, 3.4, 5.6, 8.5, 11.3, and 14.1 mA cm⁻². Based on these measurements,the areal capacitances and gravimetric capacitances were calculated, asshown in FIG. 3D and FIG. 3E, respectively, of the electrode atdifferent current densities. FIG. 3D shows the areal capacitanceretention and FIG. 3E provides gravimetric capacitance retention ofbefore and after laser treatment as a function of the applied currentdensity. All the values were measure from the full cell and calculatedbased on the electrode. Although some active materials were destroyedduring the laser scribing the microscale trenches, the LSAC electrodeexhibits better capacitance on both scales, and from both a gravimetricand an areal basis. In addition, the exemplary LSAC electrode exhibitsan excellent rate capability with capacitance retention up to a currentdensity of 25 A g⁻¹ at which the exemplary LSAC electrode delivers 6times larger capacitance compared to the non-scribed electrode. Theexcellent rate capability of the exemplary LSAC electrode is furtherverified by the electrochemical impedance measurements. The resultsindicate that the LSAC electrode exhibits a lower equivalent seriesresistance (ESR), obtained from the real axis intercept of the Nyquistplot as shown in FIG. 3F. FIG. 3F provides exemplary Nyquist plots ofthe LAC supercapacitor and non-scribed supercapacitors over a frequencyrange of 1 MHz to 0.1 Hz. In addition, the Nyquist plot of the exemplaryLSAC electrode is a straight and vertical in the low frequency region,possibly indicating ideal capacitive behavior. These results may implylow charge transfer resistance at the electrode/electrolyte interfaceand may suggest rapid electron and ion transport within the LSACelectrode. This may be ascribed to the large macroporous surfaces of theelectrode that are easily accessible to the electrolyte ions.

In another aspect, the present disclosure provides for supercapacitorscomprising redox electrolytes. In some embodiments, the redoxelectrolyte comprises a ferricyanide/ferrocyanide electrolyte, whichadds more capacitance to the cell and allows operation at a high voltageof 2.0 V in an aqueous electrolyte. In some embodiments, thesupercapacitor comprises aluminum current collectors, which are used inthe manufacturing of supercapacitors and lithium ion batteries.

In some embodiments, the supercapacitor comprises a supercapacitor coincell comprising activated carbon electrodes coated on aluminum and anaqueous 1.0 M Na₂SO₄ electrolyte without any redox additives. FIG. 4shows exemplary voltammetry (CV) of activated carbon electrode (preparedon aluminum current collector) in 1.0 M Na₂SO₄ measured at 50 mV s⁻¹ andrepeated for 6 cycles. The device was assembled and tested in a CR 2032coin cell. The figure shows the rapidly changing CV profiles associatedwith an increase of the ESR after each cycle, which may suggest thecorrosion of the aluminum in 1.0 M Na₂SO₄.

In some embodiments, the supercapacitor comprises a supercapacitor coincell comprising activated carbon electrodes coated on aluminum andaqueous 1.0 M Na₂SO₄ electrolyte with [Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻] redoxadditive. The supercapacitor exhibits a very stable electrochemicalperformance even at a high voltage of 2.0 V. A possible explanation isthat [Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻] works as a solution buffer and maintains aneutral pH (7.1) during charging and discharging. Note that 1.0 M Na₂SO₄has a pH of 6. It is also possible that the redox additive acts as asacrificial anode and thus protects the aluminum from corrosion.

FIG. 5 shows the exemplary electrochemical performances of coin cellactivated carbon supercapacitors at different concentrations of theredox additive in 1.0 M Na₂SO₄, briefly denoted as x M RE, where x isthe molar concentration of the additive. FIG. 5A presents exemplary CVprofiles collected with 0.1 M RE at an increasing voltage window from 1V to 2 V with an interval of 0.2 V and a scan rate 50 mV s⁻¹. The CVprofiles show no significant increase in the current, especially in thehigh voltage end, which signifies that there is no decomposition of theelectrolyte, and suggests that 2.0 V can be safely applied to asupercapacitor operating in this electrolyte. Both Na⁺ and SO₄ ²⁻ ionshave strong solvation energy which stems from the fact that sulfate ionscan be surrounded by 12-16 molecules of water. Therefore, it is possibleto assume that the energy that causes the decomposition of water intraditional aqueous electrolytes is now used to break the bonds in thesolvation shell of Na⁺ and SO₄ ²⁻ ions or even to drive redox reactionsof the redox electrolyte. The combination of theferrocyanide/ferricyanide redox couple with an electrolyte having highsolvation energy can explain the electrochemical stability of thesupercapacitor, even when tested at 2.0 V where water molecules wouldnormally decompose. Moreover, FIG. 5A shows a reversible redox couple(between 0.6 V and 1.1 V) which may be attributed to the redox additive.This reaction is described in the following equation:

Fe(CN)₆ ⁴⁻↔Fe(CN)₆ ³⁻ +e ⁻

For the positive side, the electrolyte undergoes an oxidation processfrom Fe(CN)₆ ⁴⁻ to Fe(CN)₆ ³⁻ during charging course, while thedischarging process induces a reduction process from Fe(CN)₆ ³⁻ toFe(CN)₆ ⁴⁻.FIGS. 5B and 5C provide exemplary electrochemical performances of thesupercapacitor comprising a redox electrolyte at various concentrationsof the redox electrolyte (RE), namely 0.025 M, 0.05 M, and 0.1 Mcompared with a traditional acetonitrile-based electrolyte, at a scanrate of 50 mVs⁻¹. With increasing concentration of RE ions, the areaunder the CV curves as shown in FIG. 5B, and discharge time of the CCcurves as shown in FIG. 5C increase, which indicates a specificcapacitance increase. By increasing the concentration to 0.2 M, the cellshowed a 1.2 times increase in capacitance compared to 0.1 M althoughthe columbic efficiency dropped to 58% as shown in FIG. 7. The highleakage current at this high concentration may increase the timenecessary for the device to reach 2.0 V during charging. According tothese results, the 0.1 M RE system is down selected for furtheroptimization of the overall supercapacitor performance. Not only doesthe 0.1 M RE system show the highest capacitance but also it has thebest rate capability. FIG. 5D provides an exemplary specific capacitanceby area vs. current density for an activated carbon electrode in 1 MNa₂SO₄ containing different concentrations (0, 0.025, 0.050, and 0.100M) of the redox additive. The exemplary 0.1 M RE system shows anultrahigh areal capacitance of 335 mF cm⁻² at 8.5 mA cm⁻² and 325.2 mFcm⁻² at a higher current density of 56.5 mA cm⁻², which is 11.6 timeslarger than the standard 1.0 M TEABF₄ in ACN electrolyte as shown inFIG. 5D. FIG. 5E shows that the exemplary 0.1M RE device maintains idealCV shapes at different scan rates of 30, 50, 70, 100, 200, and 300 mVs⁻¹. More importantly, the curves show distinct and reversible redoxpeaks at all the scan rates, which may indicate a rapid charge transferbetween the electrodes and the redox electrolyte. In addition, thisexemplary redox supercapacitor continues to provide high dischargecurrents with small IR drops, as shown in FIGS. 8A and 8B. These resultsmay imply that the 0.1 M RE electrolyte promotes rapid electron transferand an improved rate capability. This rapid electron transfer is furtherconfirmed by the Nyquist plot per FIG. 3F, of the exemplary 0.1 M RE-SCsystem, whereas the ESR is much lower (1.61Ω) than the ACN electrolyte(3.52Ω). FIG. 3F provides exemplary Nyquist plots of the 0.1 M REaqueous electrolyte and 1.0 M TEABF₄ in ACN supercapacitors over afrequency range of 1 MHz to 0.1 Hz. All the electrochemical experimentswere measured in a CR2032 coin cell.

The addition of the RE electrolyte may have the following advantages:acting as a solution buffer to maintain a neutral pH, allowing theoperation of the electrolyte with widely used aluminum currentcollectors; extending the operating voltage window up to 2 V in anaqueous electrolyte; increasing the energy density; increasing the arealcapacitance of the device through fast and reversible faradaicreactions; providing for fast electron transfer and increased ionconductivity; allowing for a higher rate capability; and decreasing theESR.

In one aspect, the present disclosure provides for carbon-based highenergy storage devices such as supercapacitors, comprising at least onelaser-scribed activated electrode and at least one redox electrolyte. Insome embodiments, the carbon-based supercapacitor comprising at leastone LSAC electrode and at least one redox electrolyte has a highercapacitance than a carbon-based supercapacitor without a redoxelectrolyte. In some embodiments, the carbon-based supercapacitorcomprising at least one LSAC electrode and at least one redoxelectrolyte can operate at a high voltage of 2.0 V. In some embodiments,the carbon-based supercapacitor comprising at least one LSAC electrodeand at least one redox electrolyte can have a high areal capacitance,high specific power, high specific energy, low ESR, or any combinationthereof.

In some embodiments, the redox electrolyte comprises about 0.1M of aferricyanide/ferrocyanide redox couple. In some embodiments, thecarbon-based supercapacitor comprising redox electrolyte can have acapacitance of about 8-fold the capacitance of a carbon-basedsupercapacitor without a redox electrolyte.

In some embodiments, the carbon-based supercapacitor comprising at leastone LSAC electrode and at least one redox electrolyte can have an arealcapacitance of about 379 mF cm². In some embodiments, the carbon-basedsupercapacitor comprising at least one LSAC electrode and at least oneredox electrolyte can have an areal capacitance of at least about 360 mFcm². In some embodiments, the carbon-based supercapacitor comprising atleast one LSAC electrode and at least one redox electrolyte can have anareal capacitance of at most about 390 mF cm².

In some embodiments, the carbon-based supercapacitor comprising at leastone LSAC electrode and at least one redox electrolyte can have aspecific power of about 5.26 W cm³. In some embodiments, thecarbon-based supercapacitor comprising at least one LSAC electrode andat least one redox electrolyte can have a specific power of at leastabout 1.0 W cm³. In some embodiments, the carbon-based supercapacitorcomprising at least one LSAC electrode and at least one redoxelectrolyte can have a specific power of at most about 6.0 W cm⁻³.

In some embodiments, the carbon-based supercapacitor comprising at leastone LSAC electrode and at least one redox electrolyte can have aspecific energy about 9.05 mWh cm³. In some embodiments, thecarbon-based supercapacitor comprising at least one LSAC electrode andat least one redox electrolyte can have a specific energy at least about6 mWh cm⁻³. In some embodiments, the carbon-based supercapacitorcomprising at least one LSAC electrode and at least one redoxelectrolyte can have a specific energy at most about 10 mWh cm⁻³.

In some embodiments, the carbon-based supercapacitor comprising at leastone LSAC electrode and at least one redox electrolyte can have an ESR ofabout 0.9Ω. In some embodiments, the carbon-based supercapacitorcomprising at least one LSAC electrode and at least one redoxelectrolyte can have an ESR of at least about 0.5Ω. In some embodiments,the carbon-based supercapacitor comprising at least one LSAC electrodeand at least one redox electrolyte can have an ESR of at most about 4Ω.

FIG. 6A-6I provide exemplary electrochemical performances of asupercapacitor comprising a combining at least one laser scribedactivated carbon (LSAC) electrode and [Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻]redox-active electrolyte (RE). The macroporous structure of the LSAC mayallow easy access of the RE ions to the surface of activated carbonparticles and enable fast and reversible redox reactions as well as fastabsorption and desorption as illustrated in FIG. 6A. FIG. 6A illustratesthe charge storage mechanism in LSAC electrode using 1.0 M Na₂SO₄electrolyte (1) in the absence, and (2) in the presence of redoxadditive. Therefore, the combination of 0.1 M RE electrolyte with theLSAC electrodes may be expected to not only boost the energy and powerbut also stabilize the cycle life, allowing the operation of the deviceat a high voltage of 2.0 V. It is also interesting to note that theexemplary 0.1 M RE system shows an ideal CV profile with a rectangularshape and distinct redox peaks, whereas an exemplary ACN electrolytesystem shows EDLC properties only as expected, as shown in FIG. 6B. FIG.6B provides exemplary CV profiles comparing the electrochemicalperformance of activated carbon electrodes before and after laserscribing tested in traditional 1.0 M in acetonitrile and in 0.1 M redoxelectrolyte, data collected at a scan rate of 50 mV s⁻¹. Furthermore,compared with exemplary 0.1 M RE with non-scribed activated electrodes,the exemplary 0.1 M RE-LSAC system shows about a 30% increase in thearea of the CV. This may suggest that the combination of an LSACelectrode with an RE can increase the capacitance through the porousarchitecture of the electrode to allow better exposure of the activematerials to the RE ions. Again, both the CV and CC measurements arecollected at an increasing voltage window up to 2 V, at a scan rate of50 mV s⁻¹ for the CV curves and at a current density of 11.3 mA cm⁻² forthe CC curves as shown in FIGS. 9A and 9B.

In some embodiments, the supercapacitor hybrid of the exemplary 0.1 MRE-LSAC is tested over a wide range of scan rates from 30 to 1000 mVs⁻¹, as shown in FIG. 6C and FIG. 9C, and current densities 8.5 to 56.5mA cm⁻², as shown in FIG. 6D and FIG. 9D. This exemplary hybrid systemexhibits redox peaks up to a high scan rate 1000 mV s⁻¹, which mayindicate excellent charge storage through ultrafast redox reactions.Change of the areal capacitances as shown in FIG. 6E, and gravimetriccapacitances as shown in FIG. 9E of all four systems as a function ofthe current density were calculated for comparison. Not only did theexemplary ACN with non-scribed electrode system show a lowercapacitance, but also its capacitance rapidly dropped at highercharge-discharge rates. Nevertheless, no significant changes can beobserved in the capacitance of the exemplary hybrid system at highrates. In order to get a glimpse of the difference between the twocases, the capacitance of the two exemplary devices were compared at arelatively high current density of 56.5 mA cm⁻². The exemplary hybridsystem can deliver 364.6 mF/cm⁻², which is 13 times greater than thecapacitance of a traditional supercapacitor using non-scribed activatedcarbon electrodes and an acetonitrile-based electrolyte (28 mF cm⁻²).Again, this may confirm the improved ion diffusion kinetics within thelaser scribed electrodes and the excellent faradaic capacitancecontribution of the redox electrolyte.

The superior synergetic interaction between the exemplary laser scribedmacroporous electrodes and the 0.1 M RE is further confirmed fromelectrochemical impedance spectroscopy measurements, showing low ESR of0.9Ω as shown in FIG. 6F and a short response time of 1.96 s as shown inFIG. 9F, compared with 1.61Ω and 3.33 s for a supercapacitor consistingof exemplary non-scribed AC electrode and 0.1 M RE and 2.6Ω and 2.07 sfor a supercapacitor consisting of laser scribed AC electrodes withoutredox additive (not shown). Apparently, the laser scribed electrodes maywork together with the redox additive towards improving both the ESR ofthe cell and the response time, which is consistent with the exemplaryCV and CC results.

The exemplary 0.1 M RE-LSAC system shows excellent performance in theRagone plot, compared with commercially available energy storagedevices, as shown in FIG. 6G. This Ragone plot is normalized based onthe volume of the full device that includes the active material, currentcollector, separator, and electrolyte. The exemplary 0.1 M RE-LSACsupercapacitor can demonstrate a volumetric energy density of 6.2 mWhcm⁻³, which is about 9 times higher than a commercially availableactivated carbon electrochemical capacitor with an ACN electrolyte.Furthermore, the exemplary 0.1 M RE-LSAC can deliver ultrahigh powerdensities up to 3.6 W cm⁻³, which is about 700 times faster than alithium thin-film battery. Therefore, the exemplary LSAC electrode incombination with a 0.1 M RE may be a perfect candidate for the futureenergy storage application.

Another Ragone plot based on the total mass of the active materials(Activated carbon and RE electrolyte) was made to compare withpreviously published RE-based electrolyte supercapacitors as shown inFIG. 6H. When compared to other published data, the supercapacitors liein the upper-right side of the plot, meaning that both the power and theenergy densities are outstanding. Even at a very high power density of11.5 kW kg⁻¹, the exemplary 0.1 M RE-LSAC maintains 95% of its originalenergy density at low rates (18.9 Wh kg⁻¹). Since the redox electrolytemay contribute to charge storage just like the active electrodematerial, the mass of the electrolyte is also considered in thecalculations. Here, the specific power achieved by the exemplary 0.1 MRE-LSAC supercapacitor is 11,516 W kg⁻¹, which is 70 times larger thanprevious reports of RE-EC.

Table 1 provides a summary of the electrochemical data for previouslypublished redox supercapacitors with aqueous electrolyte, data indicatethat the exemplary hybrid 0.1 M RE-LSAC system show higher voltagewindow as well.

TABLE 1 Comparison of the voltage window of 0.1M redox-activeelectrolyte (RE) with the exemplary laser scribed activated carbonelectrode (LSAC) with other published article using aqueous basedredox-active electrolyte Redox Couple Based Electrolyte Voltage 0.1MPotassium ferrocyanide 1M Na₂SO₄   2 V (FeCN₆ ³⁺/FeCN₆ ⁴⁺) 0.38Mhydroquinone 1M H₂SO₄   1 V (Q/HQ) 0.3 g VOSO₄ 1M H₂SO₄ 0.8 V (VO²⁺/VO₂⁺) 0.050 g p-phenylenediamine 2M KOH   1 V(p-phenylenediamine/p-phenylenediimine) 0.08M KI 1M H₂SO₄   1 V (I⁻/I₃⁻) 0.08M KI 1M Na₂SO₄   1 V (I⁻/I₃ ⁻) 0.08M KBr 1M H₂SO₄   1 V (Br⁻/Br₃⁻) 0.06M CuCl₂ 1M HNO₃ 1.35 V  (Cu²⁺/Cu) 0.4M hydroquinone 1M H₂SO₄ 0.8V (Q/HQ) 0.4M CuSO₄ 1M H₂SO₄ 0.8 V (Cu²⁺/Cu) 1M KI and 1M VOSO₄ 0.8 V(I⁻/I₃ ⁻) and VO²⁺/VO₂ ⁺) 0.4M KBr/0.1M HVBr₂ 1.2 V (Br⁻/Br₃ ⁻ andHV²⁺/HV⁺) 1M KBr/0.5M MVCl₂ 1.4 V (Br⁻/Br₃ ⁻ and MV²⁺/MV⁺)

Good cycling life is one of the fundamental properties ofsupercapacitors. FIG. 6I shows the cycle life of the exemplary 0.1 MRE-LSAC supercapacitor during charging and discharging at a currentdensity 30 mA cm⁻² for 7000 cycles. Compared with a supercapacitorutilizing 1.0 M Na₂SO₄, which loses most of its capacitance in the first10 cycles, the exemplary 0.1 M RE-LSAC supercapacitor maintains 80% ofits original capacity after 7000 cycles at 2.0 V. This outstandingelectrochemical stability can be attributed to the redox-electrolytethat not only adds faradaic capacitance to the cell but also stabilizesthe cycle life of the cell even at an ultrahigh voltage of 2.0 V. Theseresults confirm the synergy between the macroporous activated carbonelectrode formed by laser scribing and the redox electrolyte throughimproved ion migration and fast and reversible redox reactions. Themicroscale channels may act as electrolyte reservoirs and may tend toreduce the internal resistance and increase the capacitancesimultaneously.

In one aspect, the present disclosure provides processes, methods,protocols etc. for manufacturing carbon-based electrodes for use in highenergy storage devices such as supercapacitors. In some embodiments, theprocesses, methods, and/or protocols increase the capacitance of thecarbon electrodes. In certain embodiments, the increase capacitance ofthe carbon electrodes reduces the cost of storing energy in high energydevices using the carbon electrodes such as supercapacitors.

In some embodiments, the carbon-based electrodes comprise carbon-coatedcurrent collectors. In further embodiments, the methods comprise laserirradiation of carbon-based electrodes. In some embodiments, the laserirradiation of carbon-based electrodes can be performed using standardlaser cutting tools that are widely utilized in industry.

In some embodiments, the laser-irradiation of the carbon-coatedelectrodes forms micro-channels in the electrodes. The micro-channelscan store electrolytes for effective charge and discharge. Themicro-channels may reduce the distance over which the ions have to moveduring the processes of charge and discharge.

In some embodiments, the method comprises receiving a carbon substrate;casting the carbon substrate on a current collector; generating a lightbeam having a power density to generate one or more micro-channels inthe carbon substrate; and creating an activated carbon-based electrodewith one or more micro-channels.

In other embodiments, the method further comprises a light beam with apower of about 7 W. In some embodiments, the method comprises a lightbeam with a power of no greater than about 40 W. In other embodiments,the method comprises a light beam with a power of no less than about 1W.

In some embodiments, the carbon substrate comprises carbon cloth, carbonfiber, glassy carbon, carbon nanofoam, carbon aerogel, or combinationsthereof. In some embodiments, the carbon substrate is carbon cloth.

In some embodiments, the current collector is metallic. In someembodiments, the current collector comprises aluminum, nickel, copper,platinum, steel, or combinations thereof. In certain embodiments, thecurrent collector comprises aluminum.

In some embodiments, the one or more micro-channels have a pore sizefrom about 50 nanometers to about 500 micrometers. In some embodiments,the pore size is at least about 50 nanometers. In some embodiments, thepore size is at most about 500 micrometers. In some embodiments, the oneor more channels have a pore size of about 100 micrometers. In someembodiments, the one or more channels have a pore size of at least about100 micrometers. In some embodiments, the one or more channels have apore size of at most about 100 micrometers.

In some embodiments, the LSAC electrode can have an areal capacitance ofabout 50 mF/cm² to about 800 mF/cm². In some embodiments, the LSACelectrode can have an areal capacitance of about 50 mF/cm². In someembodiments, the LSAC electrode can have an areal capacitance of about800 mF/cm².

In some embodiments, the LSAC electrode can have a gravimetriccapacitance of about 80 F/g to about 150 F/g. In some embodiments, theLSAC electrode can have a gravimetric capacitance of at least about 80F/g. In some embodiments, the LSAC electrode can have a gravimetriccapacitance of at most about 150 F/g.

In some embodiments, the LSAC electrode can have a packing density ofabout 0.1 g/cm³ to about 1.0 g/cm³. In some embodiments, the LSACelectrode can have a packing density of at least about 0.5 g/cm³. Insome embodiments, the LSAC electrode can have a packing density of about0.6 g/cm³.

In an exemplary embodiment, activated carbon electrodes are prepared bymaking a slurry consisting of activated carbon, a 1:1 ratio ofcarboxymethyl cellulose/styrene-butadiene rubber, as a binder, and asolution of carbon black in deionized water with a weight ratio of80:10:10, respectively. The slurry may then be cast on a carbon coatedaluminum foil using a doctor blade method. This film may then be driedfor 12 hours under ambient conditions. The dried film may then beexposed to a 7-W CO₂ laser to synthesize laser-scribed activated carbon(LSAC) film.

In an exemplary embodiment, LSAC electrodes are assembled in a standardCR2032 coin cell using electrode discs of about 15 mm in diameter andCelgard 3501 polymer separators. The coin cells may be assembled in air.The loading masses of the exemplary activated carbon film before andafter scribing are 3.9 and 3.2 mg/cm², respectively.

In some exemplary embodiments, the LSAC-supercapacitor comprises anaqueous electrolyte. In some embodiments, the aqueous electrolytecomprises tetraethylammonium tetrafluoroborate (TEABF4) in acetonitrile(ACN). In further embodiments, the aqueous electrolyte comprises 1.0 Mtetraethylammonium tetrafluoroborate (TEABF4) in acetonitrile (ACN). Inother embodiments, the aqueous electrolyte comprises[Fe(CN)6³⁻/Fe(CN)6⁴⁻]. In further embodiments, the aqueous electrolytecomprises [Fe(CN)6³⁻/Fe(CN)6⁴⁻] in an Na₂SO₄ solution.

In some embodiments, the supercapacitor can be assembled without anyspecial dry rooms or glove boxes.

In another aspect, the present disclosure provides processes, methods,protocols for manufacturing high energy storage devices such assupercapacitors comprising redox active electrolytes. In someembodiments, the supercapacitors comprise one or more of the redoxactive electrolytes listed in Table 1. In some embodiments, the use ofredox active electrolytes increases the capacitance of the high energystorage devices. In certain embodiments, the increase in the capacitanceof the high energy storage devices reduces the cost of the high energystorage device.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

Terms and Definitions

As used herein, the term “about” or “approximately” refers to anacceptable error for a particular value as determined by one of ordinaryskill in the art, which depends in part on how the value is measured ordetermined. In certain embodiments, the term “about” or “approximately”means within 1, 2, 3, or 4 standard deviations. In certain embodiments,the term “about” or “approximately” means within 10%, 9%, 8%, 7%, 6%,5%, 4%, 3%, 2%, 1%, 0.5%, or 0.05% of a given value or range.

As used herein, the term “channel” refers to a gutter, groove, orfurrow.

1. A method of forming a laser scribed activated carbon electrode,comprising: (a) casting an activated carbon substrate on a currentcollector having a carbon-based coating, to form an activatedcarbon-based electrode; and (b) directing a laser beam towards theactivated carbon-based electrode to scribe one or more channels in theactivated carbon-based electrode to form the laser scribed activatedcarbon electrode.
 2. The method of claim 1, wherein the laser beam has awavelength of from about 375 nanometers to about 10 micrometers.
 3. Themethod of claim 1, wherein the laser beam has a power of from about 0.01W to about 100 W.
 4. The method of claim 1, wherein the activated carbonsubstrate comprises activated carbon, activated charcoal, activatedcarbon cloth, activated carbon fiber, activated glassy carbon, activatedcarbon nanofoam, activated carbon aerogel, or any combination thereof.5. The method of claim 4, wherein the activated carbon substrate furthercomprises a binder.
 6. The method of claim 1, wherein the currentcollector comprises aluminum, nickel, copper, platinum, iron, steel,graphite, carbon cloth, or combinations thereof.
 7. The method of claim1, wherein the one or more channels have a pore size of from about 50nanometers to about 500 micrometers.
 8. The method of claim 1, whereinthe carbon-based coating comprises amorphous carbon.
 9. The method ofclaim 1, wherein the activated carbon substrate is chemically activated,physically activated, or a combination thereof.
 10. The method of claim9, wherein the activated carbon substrate comprises activated carbon,activated charcoal, activated carbon cloth, activated carbon fiber,activated glassy carbon, activated carbon nanofoam, activated carbonaerogel, or any combination thereof.
 11. The method of claim 1, whereinthe activated carbon substrate comprises carbon derived from one or morecoconut shells.
 12. The method of claim 1, wherein the current collectoris metallic.
 13. The method of claim 12, wherein the current collectorcomprises aluminum, nickel, copper, platinum, iron, steel, graphite,carbon cloth, or combinations thereof.
 14. The method of claim 1,wherein the current collector is non-metallic.
 15. The method of claim1, wherein casting the activated carbon substrate on the currentcollector is performed by a doctor blade method.
 16. The method of claim1, further comprising drying the activated carbon-based electrode beforedirecting the laser beam towards the activated carbon-based electrode.17. The method of claim 16, wherein the drying is performed for 12 hoursunder ambient conditions.
 18. The method of claim 1, wherein directingthe laser beam towards the activated carbon-based electrode formsmacropores within the activated carbon-based electrode.
 19. The methodof claim 1, wherein the activated carbon-based electrode has a packingdensity of about 0.1 g/cm³ to about 1.0 g/cm³.
 20. The method of claim1, wherein the activated carbon-based electrode has an areal capacitanceof about 50 mF/cm² to about 800 mF/cm².